Federation, the ability for having your own jabber network contactable by google talk users and vice-versa, that was (partially) turned off, after a string of spam abuses.
Killing imap would cause 60-year-olds I know to complain at the same time that we would complain. You can't have that broad spectrum complaint. As much fuss as there was over whatever that RSS thing was, I signed up and used it for 6 months and then forgot it existed.
In short: Let's put to bed the idea that Google is arbitrary, they're not. If they look at the numbers and see people not really using the product, they take it out back and put a hollow point through its head. (This is also why I'm bullish about Google Plus...they would have killed it otherwise.)
Ask them about IMAP and their response would be "What??". Your point doesn't support itself.
I tried to type out another paragraph but it was equally as bad. Here is another shot at what I'm trying to get at: They're not the same because I'm willing to bet there are orders of magnitude more users using imap than there were technical people who used and cared about Jabber. Even as a technical person, I hadn't realized Google had removed it and I'm someone who previously used it. And I'm in the small group, not the general public, but I know several people off the top of my head that aren't technical and myself that use imap on a daily basis.
On the other hand, disabling IMAP will make sure that people have to look at the webapp, and tie into the Google ecosystem to read their mail. Looking forward five more years, you might even have to have a Google+ account to read your email.
(1) I don't have a server where I can run my own mail infrastructure -- I don't think my ISP would be happy with me running a mail server off my cable modem). And
(2) I don't trust Outlook.com not to silently discard mail from randomly selected senders (as I believe Hotmail was known to do). Gmail is reliable.
But otherwise, I'm ready. I've already stopped using the Gmail web interface (retaliation for killing Google Reader). And once I'm no longer tied to Gmail anymore, I can switch to a better IMAP client than Thunderbird.
I like their web UI better than GMail. It is cleaner than GMail and much faster most of the time. It's also worth noting that they now have a beta version of a calendar (with CalDAV) support:
http://blog.fastmail.fm/2014/01/23/calendar-now-available-on...
And they are apparently working on CardDAV.
- the spam filter is not very effective. I have marked as spam a certain kind of spammy newsletters many times but they still come throught.
- No calendar or contacts you can sync to your phone.
Why haven't I left already? Because it works fine and does everything I need.
Why would I leave? The way you ask, you seem to think it's obvious, but I have no idea.
I'd probably bounce back to hosting my own IMAP and using some utility to download my Gmail to it with Push or whatever protocol (HTTP?) that Gmail uses for push.
It would be nice to have Sieve scripts again to filter my mail (Gmail's filtering leaves much to be desired).
And I seriously doubt it will lose 40% even. It's not like people have many decent options for webmail + mobile mail, especially if you exclude paying for it.